Mineral oil containing a rare earth metal diester phosphate



United Stes This invention relates to a new class of-chemical compounds which are useful as addition agents to lubricating oils and oil compositions containing the same, and more particularly the invention relates to mineral oil compositions containing a rare earth metal salt of a diester of o-phosphoric acid. By the term rare earth metal salts, we mean the salts of the elements of atomic numbers 57 to 71, inclusive. The rare earth elements thus include lanthanum, cerium, praseodymium, neodymium, samariu'm, europium, gadolinium, terbium, dysprosium, holmin m, erbium, thulium, ytterbium and lutecium. The mineral oil compositions of this invention have improved pour point and' viscosity index characteristics.

The viscosity-temperature relationship of a lubricating oil isfone of the'more important characteristics ofari oil linl thjat it is th'isrelationship which is indicative of the relativeichange viscosity of an oil'at high and low temperatures. As might beex'pe'cted, the viscosity of a I mineral lubricating oil changes rapidly with a change. in

jits temperature. .In general, mineral oils tend to become .thinner as"their.t emperature increases and'thicker' as their ternperature decreases. The change in viscosity with'temperatureisgreater with some.oils'thanwith'others. While motor oils ofthe type known as crankeas'eflo'ils, it ;,desirable fori the oil to have a viscosity which issuincie ntly. high at an elevated temperature to provide adefture toprovide ease of engine; starting. lncreasingithe omechange is tolerable, excessive change, is' undesirable.

aren't 2,983,679 Patented May 9, 1961 and a minor amount of a rare earth metal salt of a diester of o-phosphoric acid has a greatly improved pour point.

The lubricating oil to which the viscosity index improving agent is added according to the invention is advantageously a highly refined parafiinic oil. Bythe term highly refined paraffinic oil we mean a petroleum lubricating oil which has been refined by one of the more drastic refining methods known in the art, for example,

by conventional aluminum chloride refining or by solvent extraction adaptedto remove all or substantially all of the unsaturated and naphthenic constituentsof the oil. Aluminum chloride refined or solvent extracted parafiinic base oil, such as a Pennsylvania oil, provides an excellent base oil for the composition of the invention. However, drastically refined Mid-Continent and GulfCoastal oil may also be 'used; While the-highly refined parafiinic oils are particularly desirable for use in forming crankcase lubricants we do not wish tolimit the'invention to these oils alone, however inasmuch as'the' rareearth metal salt of a diester of o-phosphoric acid as hereinafter defined is also useful in improving the-viscosity index and pour point of oils derived from naphthenic and asphaltic crudes.

The rare earth metal salts ofthe o-phosphorioacid esters which can be used in accordance with the invention are"those which are soluble in hydrocarbon; oils and'insoluble inwater. In this regard, we prefer to employ a rare-earth metal salt of a diester of o-phos'phoric acid wherein the ester substituent's'comprise one short'chain aliphatic" radical and one longl chain aliphatic radical. The sh'ort chain radical preferably containsjfrom 1 .t013

' carbon atorns and the long chain radical preferably conhigh temperature viscosity ofan oilwhile decreasingit's ,low temperature viscosityv can be accomplished only improving-the viscosity-temperature relationship, .or stated ,difle l n y, by a s n t e v sc y ex 9 hs e l In order to reduce excessive change in viscosity;

developed. I-In the past, for example, polymerized esters .theiryviscosity index improving characteristics is lost or substantially reduced when-the oil' inwhich, they arein- .corpora'ted isdsubjected to vigorous agitation andhigh 'shear rates and stresses. It is believed tha t the lowering 1 .of the viscosity indexofan oil 'c'ontaininga long chain polymeryasj aviscosity. index improving:v agent his a result 1. 1. of such polymer being split into polymers of shorter ich'ain 'lejngth by'the shearing stress"; thef shorter chain 'lymers being less effective as? viscosity index impibvei's. We have found'that a rare earth metal: salt of a diester proving characteristics to a mineral'joihanddhat"the .mdjex e n I wtav ie n e e w r ew g an esses o-phosphoric" acid imparts excellentfvisc'osity index man facilitates dehydiatio wins from" 8 to 20 carbonatoms. The length of-the re s'peetive' chains-is determined by thesolubility of the resultant compound in mineral oil. The limit of solu 'bility is believedte be r'e'ached-wlien the long; aliphatic chain; contains horrid-4 to l6 carbon atoms for'a saturated 'group'and from 18 to '20 c'arbona'tom's' or moreifor an unsaturated group."

The rare earth metal salt of the diester of O-phosphoric acid can be prepared by any suitable method; According to" a preferred procedure, the "rare earth metal-salt of the o-pbosphoric acid ester is prepared'by reacting abas'ic rare earth metal compound with anacidic o-phosphoric acid ester." The rare earth metal compduna is employed amount s'ufiicient toefleet completeneutralization sen allysafwith th'e e yolutionof heatf nether-ii stances'jhiiwever, it is'requir'ed' 'to addadditional heat "formation is-substantially complete, themixtu're is further heated for a time s'uffi'eient to expel the water of neutralimean: The use of a slight :va'cuu'm at'r'this lzp'oint -metal compound-Q In some instances -it is desirable "to "prepare an alkali metal. salt"off the organic phosphate and" thereafter prepare the rare earth ineta'l-gsa'lt 'by metathesis jof the alkali jrhetalfsalt} with a water-soluble'salt :ofthe 5 rare earth metal slichlas the nitrate; chlorideo1" sulfate, asfappropriate.

The rare earth metaljgco'mpound used preparing the corresponding metal salt of' the diester of o-phosphoric e o-phosph oricaeid ester. 1 In some instances, the iza'tion reaction takes place spontaneously; or 'subt p rat r v i viscosity in imprq s e e ,t effec e'omplete neutralization. In efi'ecting'comple'te W v v Thereafter, the dehydrated-1 pro. v duct is'filter'e'd toseparate out any unreacted rare-earth 3 Bare e'a z-th salts fir-m mdnazitah'c I Rare earth salts 1 b em l d B I of separating the individual elements. -Therefore; L

1 an economic standpoint it is desirable-t0 prepare the C to C 5 aliphatiqradical.

5 a hea er 1 (1 oftherareearthoxidesy-j" I may be prepared in any suitable manner; :FQr exempts;

w a mixture of a higher monohydric alcohol containing I I i from 8 to carbon atoms; a monohydricalcohol cone raining from 11035 carlsonj atoms and. phosphorus petit oxide may be refluxed; for: several hours.

I mixtureojf mono; di and =tri. esters;

htain individualpurecompounds. I

= According to; another; :ernb. dime amonnhydric alcohol weaning fioiii 8 to 20 carbon 'to'ms to form a phosphoryl monochloride which is sub equn iy hyd olyz it (id u niariifig'g lcohols, ine I i ten rs l f the lungchain it a and the other contains from 8 to 20 carbon atoms. Ex-

amples of such organic diesters of phosphoric acids are methyl; n-octyl, ethyl n-octyl, n-propyl n-octyl, isopropyl isooctyl, allyl isooctyl, methyl nonyl, ethyl nonyl, propyl nonylgmethyl decyl, ethyl Ldecyl, propyldecyL m ethyl 1, Others Ocinpnsltmnoi an; Earths,'Wt.Pereentas Oxides:

, making the rare.

' metal salts, for the purposes. of the invention also a i p h j i a; i I I chloride is reacted with a monohydric alcohol contain ng I from 1 ;to: 3' carbon atoms :to; form; the corresponding phosphor} dichloride which is thereafter reacted with 3 I o m gfl z d s r d: i j r c i 10 C2 1 aliphatic radical and, a I

I nrr ll); tetradecyl; nhex'adecyl g n 1; octadecyl .(stearyl), 'n-octade'cenyl (oleyl), n-octadcadienyl (linoleyl) and eicosyl alcohols. 'Ihe alcohols need 1 rare j metal} salt of a diesterjotg c-phcsphoric' and by 1 neutralizing lthe: o-phosphoric acid: ester with a m lxture' t e P e I e g -W i j i r arse e; and meal are: c

V esters can be employed per se orthey can added tothe 1 lubricating oil in the form of a: mine 1 man; salt can: he prepared- "can be flashed from the ml. of waterand 250ml. 059598 ethanol. To the: mix- I 1 'ture thus: :formedi are added; with stirring, 9.49 gm. sodium hydroxide .inIZOQ ;ml.- of water. Thetemperm I ture of the reaction is maintained at: about .25 C; To. I I the "reaction mass: thus; formed are slowly added 34.2 I w I gmvoflant-hanum nitratehexahydrate in 200 m1; of water with; rapid stirring; the temperature :of :the: metathesis I I reaction beingmaintained at: about. 25. C. A I yellowprecipitate is. formed. The jwater; i is decanted j a I I 1 from .the reaction: mass and thereafter. the precipitate. I I I winner-Iranian m e centimeter oxides cansuccessis dissolved in. hexane, s u on ei i i i ated by ine preparing the salt of=thejdiesterapplication of .asmall amount of heat. I Thereafter; the product is tilteredto jremo any undissolved solids; So l-. I

"tripped. sea the insan when the sol-5 1 Event is ,Scgompletely removed; an jopaquc yellowish jr uhe her-like product comprising lanthanum ethyl .oleyl pl es- I i j phatei is obtained: Analysis of the .prodnct' shows it to I compare; {357313131}! With: thi {theoretical analysis; 0f, I lanthanum ethyl oleyl orthophosphate as follows:; 5 I I I I ral oil concentrate preparing the mineral oil f ate, the rare earth n an organic solvent whic alter fo rrnation iof :the icon ntrateg s Organic solvent uitable for this? purpose Indchexane, Mc'tane; naphtha. be

.inplo'yed per; s or ing characteristics to. the oil. For example, the rare earth metal salts are useful when employed in amounts of about0.1 to about S percent by weight; I Amounts in excess of 5 percent are generally undesirable because the oil becomes too viscous for satisfactory use as crankcase lubricant. [Excellent resultshav been obtained by dodecyl, ethyl n-dodccyl (ethyl l-auryl), allyl n-dodecyl,

ethyl tetradecyl, ethyl n-hexadecyl, ethyl .n-octa'decyl "and ethyl eicosylesters of o-phosphoric acid.

Specific examples of, espccial1y effective agents for purposes of the. invention are the oil-soluble lanthanum and neodymium salts of ethyl oleyl acid orthophosphates. Other salts included by the invention are the lanthanum, neodymium, praseodymium, cerium and sarnarium salts of ethyl n-octyl, ethyl isooctyl, ethyl decyl; ethyl n-dodecyl (lauryl), ethyl n-octadecyl (stearyl) and ethyl n-octadec (ethyl 1stearyl), allyl n-octadecyl, ethyl n-octadecenyl theme in petroleumdistillates such as, SAE 10Iand SAE 25 lubricating oil, of amounts of the saltsbetween 0.1 and 0.5 percent by weight of the composition; It will be understood that the optimum amount will vary according toithe particular mineral oil and according tofthe conditions to whichtheoil is subjec'ted.

The following-examples illustrate the preparation of mineral oil concentrates of the various rare earth metal "salts etc-phosphoric acid esters. The mineral oil used in the examples is an SAE 10 highly refined parafiinic oil having a viscosityof 171 and 45.2 SUS-at IOOFF.

and "210 F; respectively; aviscosity index of 110; a flash point of 465 F.; a fire point of SOSfIFi; a pour point of and a colorg-ASTM Union of Zminus. EXAMPL -111 j I j Ngdyrnium ethyl alyl orthophosphatefi mechanicalstirier and refluxyeondenser' are placed 979 plac'edf89.2 gm. of ethyl oleyl'acid Iorthophosphatep tqp s QifgQil are added 4,09 gm. f neodymiumfixideand 26 .6 5 ofethylcleylo-phosphoricacid with 'rapid stirring. The addition r of II several cubic: centime water afllthis point is advantageousfm the speedof the reaction." The reactionmass rat-med Theoretical 1 the :ephes norie acid I i s tena mer aa; amthe: are. I I r n a mineral en;

'Q "I ate: '5 thei n fi ial? Calif 3' 3 I directly Etc the" oil to l be improved *0 can he 3 of a-rnine'ral oil concentrate, I an amount is used tif- I f 4 ficicnt toimpart viscosity index and pour point improvoil thus obtained islight in color and isfairly viscous,

comprising a 3% solution of neodymium ethyl oleyl orthophosphate in mineral oil. H 7 z EX MPLEI I; I

La n thdrihm ethyllolyl orihbpliosph izit' Into a 3 liter round bottom flask are placed 970 gm.

of an SAE 10 highly refined paraffinic oil, 26.7 gm. of '15 2' liter flask are placed i170 eras-share highly refinedparafl'inic' mineral oil, 26 .7 gm. ottiethyl oleyl orthophdsp'h'ate 30 of water 'and hydroxide obtained by reacting}? gm. of cerium nitrate ."'tif hydroxide'.j reaotion' rniass heated 5 II to" ZQQ C and' dehydrated} as in the previous ex: 5 pies; The pl oduotfeomp r'ises "a 2.5 solution of c'ieriuiif-ethyl ole'yl orthophosphate in niine'ralfoil. EXAMPLE VI r hsodyiiziuritme'thyl' oley'l ortl ophosphate a l-a5 and methyl ole'yl, drthophosplrate Enample IV,; an oil solution of praseodymiuni lorthophosphate P II j rky!- l y c zq re Szimhrium I I of Exainple III: is'- followed except arreadntixed wit ,a aniountofyvater and addedto .10 refined parafiinic "minerial san'lariumoxide is substituted-for lanthanum oxide: The

product comlprises an oil solution of saniarium ethyl oleyl'orthophosphatei' I I I l EXAMPLE vrn Lanthanum ethyl isooctyl orthophosphate The procedutre of Example IV is followed exceptethyl isooctyleorthophosphate is substituted for ethyl lauryl' phosphate. The product comprises an oil solution of lanthanum ethyl isooctyl orth'ophospha'te.

EXAMPLE 1 7 I Neodymitir'rifmthylo ,eic'osyl orthoph'asphate ethyl-oleyl o-phosphoric acid and 4.0 gm. of lanthanum Th pfdcdurerof Examplfliswfouowed except. meth; figfi z ggs isgg g' g g g gi yl eicosyl o-phosphoric acid is substituted for the ethyl WatZr is thei removed heatin ur ider a vacuum Oleyl Phosphmic .T resulting product comy g prises-an oilsolutionof'neodyniiuni-niethyleioosyl orthoat C. The heated product is then filtered to rev move excess lanthanum oxide. When the oil cools it 20 p USP 3 1 I becomes quite viscous but is still sufficiently fluid to r it 7 EXAMPLE X Q h? P FO P a f L-an'thanum propyl oleyl orthophos'phwte *h ethyl mpmphat? m7 mmeral 7 'prec'eeur e ot-Example IV is renewed-except pie EXAMPLE'IV i I pyl oleyl onthophosphate is substituted for ethyl lauryl Lanihanum e'thyl laurylorthophosphdte 'H 1 Bf-resulting P u mpnses an 'Oil solus V tionof lanthanum propyloleyl orthophosphate.

.Into a 2 hter f n b m flask P d It will be" understood that the foregoing examples are Q f SAEIO hlghly i P m mi Q -5 ninseanvsoniy and that other rare earth metal salts in-9 th l 15 m! Ph sphat and QE P- 0f ,htflhtm of dies'ter emm hosphates wherein the ester substit'iients oxide. To th s mixture are added 10 ml. of water folomp shoir-tI:.ichain aliphatic Imdical containing lowed by heating for 4 hours at 95 C. Upon comple- {Tom 1 gi -a o x long (mam-aliphatic F493 thi een the Water PY yih v radical containing from 8 to 20. oarbon atoms can be Yfi liit fl i 95 n 'hee dlfiq I employed. Specific examples of such other salts include #1 9 3}??? to m e qmpy ,T the europium, gadolinium, terbium, dysprosiu-m, holium, Q -9 1 Whlch becofnes quite vlscous w erbium',-thuliu-m, ytterbium 'and'luteeium salts of methyl -fi s v pr i ia l Qfilanthangm ethyl oleyl, ethyl oleyl, propyl oleyl, ethyl isooetyl, ethyl Iautyl orthophosphate m mmeral I I I I 'eicosyl andallyl l-auryl orthophosphoric acid: 1

v s .I r v EXAMPLE V. While the preparation of therare earthmetal salts I I iermmemyl Qleyl orthophosphate 40 emfdingto Procedure e 111 xa 11. LIX

as hexane, benzene and carbon tetrachlorideis used in place of amineral oil and is flashed off either before or after the formation' of the rare earth salt.

To demonstratetheeffectiveness ofthe rare earth metal salts of the type described above inthe mineral oil conipositions contemplated ''by this "invention, weqhave conductedseveralcomparative tests; the. results of which hare listed below}. with representative Lmineral oils alone with .sarne oils blended with; various representative 'rareearth metal salts of diest'er orthophos'phates. These tests were conducted with higmy refined par-smite mineral oils of SAE 10 and SAE 25 grade. The improvement produced by the. improving agents of the present invention inthe' viscosity index mineralfoils tive' data in'Table II.

to'whieh they are added clearly shown by the illustra- I ,TABLE II. Compositiom-Percefit by v ,J. i' e kw 9 v ,WSAE 1O.Mineral 0il'. v SAE 25 MineralOil g 5 H 99:5 99. 5 Neodymium-emit v. I I c -phosphate 0.6 Lanthanumethyl oleyl' I q p a ophosphate' I 0.5 I VISCOSITYDATA 1 "1 I a j fviscosityfcsns. J .1 i 1 l -,J "5 I M1009 F 36. 77 7,6 7 43. 89 64;: 13 38. 83. 85 94. 37 1048: 12316 234. 1 r 83. 79 at 21Q'F 5.80 5 9.5 7:28 -12.60 2.60 10.64- 12.18 14.01 16.67 30.85 18.43 Viscosity-Index 108 er. 152 113 117 '1-29 132, 133 154 The data in the above Table II clearly shows that even as little as 0.25 percent of the neodymium and lanthanum salts of ethyl oleyl o-phosphate greatly improves the viscosity index of the mineral oil.

The improvement in pourpoint is shown by the data in Table III.

o-phosph m While the neodymium salt is more effective than the lanthanum salt, the improvement with such a small amount of additive is nevertheless striking.

The ability of the oil compositions of the invention to retain their improved viscosity index characteristics even though subjected to prolonged ultrasonic irradiation is demonstrated by the data shown in Table IV. These tests were conducted with a highly refined parafiinic mineral oil of SAE 25 grade. Several comparative tests were made with. (l) the mineral oil alone, (2) with the same oil blended with a representative rare earth metal salt of a diester orthophosphate and (3) with the mineral oil containing a commercially available viscosity index improving agent of 'the polymerized acrylic series.

The improvement obtained in viscosity by the proving .agents of the present inventionis clearlyzshown by the illustrative data iii Table Iv. lt will hes noted that evenafter 120 minutes of ultrasonicirradiation, the

compositions of the inyention, i.e., Compositions Maud N, retained their improved viscosityindicesr iContrari wise, the SAE 25 oil which contained the commercially viscosity of the'compositions' of the invention both at 100 .F. and at 210"F., the irradiated compositions in every instance. had viscosities considerably abovejthe viscosity of the base oil. On the other hand;

the base oil conj- .available polymerizedacrylic ester did not retainiits initial yiscosity index even though the agent wasv present in amounts "10 to 50 times greater than-the improving agent of the invention: It will be noted. further that while ultrasonic irradiation caused some decrease in the mw at' ab t iw s pa ew position;

i at o phbsphoric ac taining the polymerized acrylic ester after ultrasonic irradiation had a viscosity even less than the viscosity of the base oil when measured at F. and substantially the'same viscosity when'measured at 210 The data thus obtained in the ultrasonic shear stability indicate that the rare earth metal salts of diester o-phosphates aresnrprisingly stable even when subjected to vigorous agitation and high shear rates and stresses. An inspection of thephysical properties of an SAE 10 mineral lubricating oil and thesame lubricating oil containing 0.25 percent by weight of neodymium ethyl oleyl o-phosphate and, 0.25 percent by weight of lanthanum eth yl oleyl o-phosphate are as follows:

Lubrleati Lubricatg 011 .lhg Oil Lubrlca- +0.25% +0.25% ing Oll neodymilanthanum um ethyl ethyl oleyl oleyl oo-phos-' phosphate phateiiz Viscosity, SUS:

at 100 F .4 y 171 207 at 210 45.2 68.8 Viscosity Index 11 152 Flash Point, 00: F 465 450 Fire Point 00: 505 505 Pour Point, +10 -20 Color, 2 minus 2 minus Neutralization Value: ASTM 13-974; 0. 01 0,17 Ash, ASTM D482, percent 0. 01 0.05

The lubricating oil composition of this invention can contain other addition agents normally added to lubricating oils for a specific purpose such as an oiliness and eittreme pressure agent, an anti-oxidant, a corrosion i nhib itor; a foamsuppressant, a dye, a sludge inhibitor, thelike. While our invention has been described with reference to various specific examples and embodiments it will be understood that the invention is not limited to such examples. and embodiments and may bevario usly practiced within the scope of the claims hereinafter made.

We claim! f Y 1. A lubricating, composition comprising ajfmajoi' amount offa mineral oil and a minor amount, sutlicieilt to impartjimprovedpviscosity index characteristics -to this composition, of a rare earth metal saltQof adieste of o-phosphoric acid wherein the rare 'earth metal'isanelement having an atomic number from 57 to 71 and the ester substituentsfl comprise one aliphaticiradical containingfrom 1 to 3 carbon atoms and one aliphatic radical containing from'8 to 20 'carbonatoms.

l wherein sa dnunor weight of the co] V 2; The' compositiomof claim 3. A lubricating comprisiri a or amount of a mineral lubricating oil and a minor amount, suflicient to impart improved viscosity inde t character.- istics to the composition, bfalanthanumsa'lt of a diester one-phosphoric acid whereinthe ester; substituen e'icomprise one aliphatic radical containing from 1 to 3 carbon atoms and. one aliphatic radical containing from 8 to 20 carbon; atoms,

4. A lubricating"composition comprising a major amount oi Ta minerallubricating oil and a minor amount,

su fl icient; toimpart improved viscosity index characteristics' to the'compo 'tion; of a neodymium salt of a diester wherein the ester substituents comprise onealiphatimradical containing from 1 to 3 car- 20 carb nL t m 1 bonvatoms and one: aliphatic radical containing from 8 to 5. ,A lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount, sufl'icient to impart improved viscosity index characteristics to the composition, of lanthanum ethyl oleyl orthophosphate.

10 References Cited in the file of this patent UNITED STATES PATENTS 2,228,658 Fanington et al Jan. 14, 1941 Downing et a1 June 9, 1942 2,480,673 Reid et al Aug. 30, 1949 OTHER REFERENCES Chem. Abstracts, vol. 52, 18064 g, Nov. 10, 1958. 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL OIL AND A MINOR AMOUNT, SUFFICIENT TO IMPART IMPROVED VISCOSITY INDEX CHARACTERISTICS TO THE COMPOSITION, OF A RARE EARTH METAL SALT OF A DIESTER OF O-PHOSPHORIC ACID WHEREIN THE RARE EARTH METAL IS AN ELEMENT HAVING AN ATOMIC NUMBER FROM 57 TO 71 AND THE ESTER SUBSTITUENTS COMPRISE ONE ALIPHATIC RADICAL CONTAINING FROM 1 TO 3 CARBON ATOMS AND ONE ALIPHATIC RADICAL CONTAINING FROM 8 TO 20 CARBON ATOMS. 